Solar cell



FIG. 1 is a top perspective view of a solar cell showing our new design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a back side view thereof; and,

FIG. 7 is a front side view thereof.

The broken lines shown represent the portions of the solar cell which form no part of the claimed design. 

CLAIM The ornamental design for a solar cell, as shown and described. 